JP2010098673A - Dielectric filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric filter which suppresses unwanted waves without deteriorating the Q factor of a dielectric resonator, even if compact. <P>SOLUTION: The dielectric filter 1 includes a conductive case 2 forming a closed space and a plurality of dielectric resonators 21-24 installed inside the case while being spaced apart from one another. The dielectric filter includes: a plurality of semi-coaxial metal resonators 25, 26 each disposed while being separated so as to be electromagnetically coupled with any one of the plurality of dielectric resonators 21-24; coupling adjustment screws 31-35 each for adjusting a degree of coupling between neighboring ones of the plurality of neighboring dielectric resonators 21-24 and the plurality of semi-coaxial metal resonators 25, 26; and frequency adjustment screws 41-46 which are installed above at least one or more dielectric resonators and semi-coaxial metal resonators and adjust a resonant frequency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dielectric filter, and more particularly to a dielectric filter combined with a semi-coaxial metal resonator.

  Conventionally, communication lines such as telephone, mobile communication, and television relay use microwaves, and these communication lines include a base station for transmitting and receiving microwaves as radio waves. In this base station, a filter for passing only radio waves in a desired frequency band and removing unnecessary radio waves is installed.

  Conventionally, a dielectric filter having a small and low loss characteristic is known as this type of filter (see, for example, Patent Document 1).

  This conventional dielectric filter includes a plurality of dielectric resonators installed in a closed space formed by a conductive casing. These dielectric resonators are separated from each other by a partition, and are electromagnetically coupled through a coupling window formed in the partition.

  The conductive housing is provided with an input / output connector to which a coupling probe is connected, and the microwave propagated from the outside of the housing is magnetically coupled to the dielectric resonator by the coupling probe, An electric field is generated inside the dielectric resonator to excite the dielectric resonator.

With such a configuration, the conventional dielectric filter has a high Q value in the dielectric resonator, so that the insertion loss before and after the pass band is rapidly increased while being small in size.
JP 2002-359502 A

  However, the dielectric filter disclosed in Patent Document 1 has a problem that it is easy to transmit unnecessary waves other than the frequency band such as spurious due to the characteristics of the dielectric resonator. Further, if the shape of the dielectric resonator is changed so that the frequency band of the unnecessary wave that is transmitted is away from the desired frequency band, the Q value of the dielectric resonator is deteriorated. Further, when a filter for removing this unwanted wave is installed without changing the shape of the dielectric resonator, there is a problem that the dielectric filter becomes large.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a dielectric filter that can suppress unnecessary waves without deteriorating the Q value of the dielectric resonator while being small.

  The dielectric filter of the present invention is a dielectric filter comprising: a conductive casing that forms a closed space; and a plurality of dielectric resonators installed in the casing and spaced apart from each other. A plurality of semi-coaxial metal resonators spaced apart so as to be electromagnetically coupled to any one of the plurality of dielectric resonators; the plurality of dielectric resonators adjacent to each other; and the plurality of semi-coaxial metal resonators; A coupling adjusting element that adjusts the degree of coupling between the at least one dielectric resonator, and a frequency adjusting element that is disposed above at least one of the dielectric resonator and the semi-coaxial metal resonator and adjusts a resonance frequency. And

  With this configuration, the dielectric filter of the present invention can rapidly increase the insertion loss before and after the passband while having a small size, as in the case where the dielectric filter of the present invention is composed of only the dielectric resonator. It is possible to suppress transmission of unnecessary waves other than the pass band, such as spurious generated in the case of being constituted only by the above.

  Furthermore, in the dielectric filter of the present invention, the dielectric resonator has a shape that is in the same operation mode as the semi-coaxial metal resonator, and the housing includes the semi-coaxial metal resonator and the dielectric. An input / output element for exciting at least one of the resonators in an operation mode of the semi-coaxial metal resonator is provided.

  With this configuration, the dielectric filter according to the present invention has a good transmission characteristic because there is no loss due to mode conversion between these resonators when a semi-coaxial metal resonator and a dielectric resonator are combined. Can have.

  Furthermore, the dielectric filter of the present invention is characterized in that the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators are disposed on the same surface of the inner wall of the casing forming the closed space. And

  With this configuration, the dielectric filter of the present invention is small and lightweight because the frequency adjusting elements for the semi-coaxial metal resonator and the dielectric resonator are installed in the same direction.

  Furthermore, the dielectric filter of the present invention is configured such that the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators adjacent to each other are partitioned by a conductive wall in which a coupling window for adjusting the degree of coupling is formed. It is characterized by being.

  With this configuration, in the dielectric filter of the present invention, the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators adjacent to each other are coupled to each other via the coupling window. By changing, the coupling degree between the resonators adjacent to each other can be adjusted.

  Furthermore, the dielectric filter of the present invention is characterized in that the degree of coupling is adjusted by adjusting the distances between the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators adjacent to each other.

  With this configuration, the dielectric filter of the present invention determines the degree of coupling between the resonators by adjusting the distances between the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators adjacent to each other, and has desired filter characteristics. Can be generated.

  Furthermore, in the dielectric filter of the present invention, at least two of the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators are the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators. The three adjacent resonators are partitioned by a conductive wall having a coupling window so as to be electromagnetically coupled to each other.

  With this configuration, the dielectric filter of the present invention has a jumping structure in which two resonators other than the preceding and following stages are coupled in addition to the coupling of two semi-coaxial metal resonators and dielectric resonators that form adjacent and preceding stages. Since coupling occurs, the insertion loss before and after the pass band can be rapidly increased, and radio waves outside the desired frequency band can be reliably attenuated. In addition, since the insertion loss before and after the pass band increases rapidly, the number of resonators installed in the housing can be reduced.

  The present invention can suppress unwanted waves without deteriorating the Q value of the dielectric resonator while being small.

  Hereinafter, a dielectric filter according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
A dielectric filter according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view schematically showing a configuration of a dielectric filter according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the filter portion in the first row in FIG.

  As shown in FIG. 1, the dielectric filter 1 according to the present embodiment functions as a six-stage filter, and is formed by a metal housing 2 having a substantially rectangular parallelepiped shape and a cylindrical dielectric. Dielectric resonators 21 to 24, semi-coaxial metal resonators 25 and 26, input-side connector 3 for inputting electromagnetic waves to the semi-coaxial metal resonator 25, and output of electromagnetic waves from the semi-coaxial metal resonator 26 The output side connector 4 is provided.

  The housing 2 includes a housing body 2a and a lid portion 2b. The housing body 2a has a plurality of cavity inner walls 51 to 56 that respectively form a plurality of cylindrical cavities. These cylindrical cavities are shielded by the lid 2b.

  The dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 are installed in a plurality of cavities with a predetermined space from the cavity inner walls 51 to 56, respectively. In the present invention, the radius and depth of the cavity inner walls 51 to 56 described above may be equal.

  Here, the dielectric resonators 21 to 24, the semi-coaxial metal resonators 25 and 26, and the cavity inner walls 51 to 56 shown in FIG. 1 are arranged in two rows on the housing body 2a. In this arrangement, it is preferable that the volume of the housing 2 is compact and the input side connector 3 and the output side connector 4 can be installed on the same side surface of the housing 2. The position of 4 is not limited to this. Note that these resonators 21 to 26 may be arranged in other than two rows, and may be arranged in one row, for example.

  The dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 are fixed to the bottom surface 2c of the housing 2 by known means such as screws so that the longitudinal directions thereof are parallel to each other. The dielectric resonators 21 to 24 are respectively supported by a low dielectric constant support (not shown), and electromagnetic waves excited by the dielectric resonators 21 to 24 constitute the cavity inner walls 51 to 56. It is not attenuated by the metal wall.

  Coupling windows 61 to 65 for coupling two resonators forming the steps before and after the adjacent ones are formed in the hollow inner walls 51 to 56 of the housing body 2a. In the present embodiment, the coupling windows 61 to 65 are positioned above the boundary portion formed by the adjacent cavity inner walls 51 to 56.

  Between the semi-coaxial metal resonator 25 and the dielectric resonator 21, a coupling adjusting screw 31 for adjusting the degree of coupling between these resonators is installed.

  Similarly, between the resonators adjacent to each other among the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26, coupling adjusting screws 32 to 35 for adjusting the degree of coupling between the resonators. is set up.

  As shown in FIG. 2, the coupling adjusting screws 31 to 35 are inserted into through holes formed in the lid portion 2 b constituting the housing 2, and are installed so that the longitudinal direction is substantially parallel to the longitudinal direction of each resonator. Has been. The coupling adjustment screws 31 to 35 slide in a direction perpendicular to the bottom surface 2c of the housing 2, and the coupling degree of each resonator depends on the insertion depth of the coupling adjustment screws 31 to 35. It has come to be adjusted.

  The coupling adjusting screws 31 to 35 may be configured by a coupling degree adjusting rod having a fixing portion for fixing at a desired insertion depth. Further, by using a male screw instead of the coupling degree adjusting rod and forming a female screw on the lid 2b of the housing 2, the coupling degree between the resonators 21 to 26 may be adjusted by the screw feeding mechanism. Good.

  The dielectric filter 1 may further include a plurality of frequency adjusting screws 41 to 46 for adjusting the resonance frequencies of the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 in the lid portion 2b. Good. In this case, as shown in FIG. 2, the center axes of the frequency adjusting screws 41 to 46 are installed so as to overlap the extension lines of the center axes of the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26, respectively. To do. By adjusting the distance between the frequency adjusting screws 41 to 46 and the resonators 21 to 26, the resonance frequencies of the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 can be changed. Become.

  In the present embodiment, as shown in FIG. 2, the diameters of the semi-coaxial metal resonators 25 and 26 are configured to be shorter than the diameters of the dielectric resonators 21 to 24. However, the diameters of the semi-coaxial metal resonators 25 and 26 and the diameters of the dielectric resonators 21 to 24 may be equal. Alternatively, the diameters of the semi-coaxial metal resonators 25 and 26 may be longer than the diameters of the dielectric resonators 21 to 24.

  The semi-coaxial metal resonators 25 and 26 are constituted by cylindrical resonant elements formed of metal such as brass, brass, aluminum, or invar, for example. Further, the semi-coaxial metal resonators 25 and 26 may be subjected to processing such as silver plating in order to increase the no-load Q. Similarly, the inner surface of the housing 2 in which the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 are installed is also subjected to a treatment such as silver plating in order to increase the no-load Q of these resonators. May be.

  The input-side connector 3 has a loop-shaped inner conductor 3a. The inner conductor 3a of the input-side connector 3 is provided in a cavity formed by the cavity inner wall 51, and inputs electromagnetic waves propagated from an external circuit to the dielectric resonators and the semi-coaxial metal resonators 21 to 26. ing.

  Similarly, the output-side connector 4 is provided in a cavity formed by the cavity inner wall 56, and outputs electromagnetic waves that have passed through the dielectric resonators and the semi-coaxial metal resonators 21 to 26 to an external circuit. . The output connector 4 has a loop-shaped internal conductor (not shown) as with the input connector 3.

  As shown in FIG. 2, the inner conductor 3 a is parallel to the longitudinal direction of the semi-coaxial metal resonator 25 in the cavity formed by the cavity inner wall 51. Here, the tip of the internal conductor 3a may be soldered to the bottom surface 2c of the housing 2 as a ground. Or the front-end | tip of the internal conductor 3a may be formed so that a front-end | tip may be in an open state, without contacting the bottom face 2c.

  Further, as in the present embodiment, the first-stage and sixth-stage resonators 21 and 26 coupled to the input-side connector 3 and the output-side connector 4 among the six-stage resonators 21 to 26 are semi-coaxial metal. When configured by a resonator, the tip of the inner conductor may be soldered to the semi-coaxial metal resonator.

  When electromagnetic waves are input from the external circuit to the dielectric filter 1 via the input side connector 3 having the above-described configuration, the semi-coaxial metal resonator 25 is excited with quasi-TEM mode electromagnetic waves. The electromagnetic wave excited in the semi-coaxial metal resonator 25 excites the dielectric resonator 21 through the coupling window 61. At this time, a mode similar to the quasi-TEM mode is excited in the dielectric resonator 21 by adjusting the diameter of the dielectric resonator 21 and the distance from the cavity inner wall 51.

  3A and 3B are diagrams showing the operation mode of the resonator. FIG. 3A is a diagram showing the operation mode of the semi-coaxial metal resonator, and FIG. 3B is a diagram showing the operation mode of the dielectric resonator.

  As shown in FIG. 3A, a semi-coaxial metal resonator is excited by a quasi-TEM mode radio wave. Further, by adjusting the diameter of the dielectric resonator, a mode similar to the quasi-TEM mode is excited in the dielectric resonator as shown in FIG.

  Therefore, the dielectric filter 1 according to the present embodiment can suppress the propagation loss due to mode conversion and obtain good propagation characteristics.

  By having the configuration as described above, the dielectric filter 1 of the present invention can rapidly increase the insertion loss before and after the passband while being small, as in the case where the dielectric filter 1 is configured only by the dielectric resonator. In addition, it is possible to suppress the transmission of unnecessary waves other than the pass band such as spurious generated when only the dielectric resonator is used.

  In addition, when the semi-coaxial metal resonators 25 and 26 and the dielectric resonators 21 to 24 are combined, loss due to mode conversion between these resonators does not occur, so that the transmission characteristics are good. it can.

  Further, since the frequency adjusting screws 41 to 46 for the semi-coaxial metal resonators 25 and 26 and the dielectric resonators 21 to 24 are installed in the same direction, the size and weight can be reduced.

  In the above description, the case where the dielectric filter 1 includes the four dielectric resonators 21 to 24 and the two semi-coaxial metal resonators 25 and 26 has been described. However, the dielectric filter 1 only needs to include at least one dielectric resonator and at least one semi-coaxial metal resonator. The required number of dielectric resonators and the number of semi-coaxial metal resonators are appropriately changed according to the use of the dielectric filter.

  In the above description, the first-stage resonator coupled to the input-side connector 3 and the sixth-stage resonator coupled to the output-side connector 4 are constituted by the semi-coaxial metal resonators 25 and 26. Although the case has been described, the present invention is not limited to this, and at least one of the first-stage resonator and the sixth-stage resonator may be a dielectric resonator. Further, any one of the six-stage resonators only needs to be constituted by a semi-coaxial metal resonator, and the first to sixth-stage resonators, the dielectric resonator, and the semi-coaxial in the present embodiment. The correspondence with the metal resonator is only an example.

  In the above-described embodiment, the semi-coaxial metal resonators 25 and 26 are coupled to one adjacent dielectric resonator, and the dielectric resonators 21 to 24 are adjacent to each other, that is, the front and rear stages. The case of coupling with each other has been described. However, the present invention is not limited to this, and as in the second embodiment to be described next, the dielectric resonators 21 to 24 are adjacent so as to be coupled with resonators other than the preceding and following stages. It may be coupled with three matching resonators.

(Second Embodiment)
A dielectric filter according to a second embodiment of the present invention will be described with reference to FIG.

  The configuration of the dielectric filter 81 according to the second embodiment is substantially the same as the configuration of the dielectric filter 1 according to the above-described first embodiment, and each component is shown in FIG. The same reference numerals as those in the first embodiment will be used, and only differences will be described in detail.

  In FIG. 4, an arrow A between the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 indicates that two of the resonators 21 to 26 that are adjacent to each other and form a front and rear stage. It represents the electromagnetic coupling between the units.

  The dielectric filter 81 according to the present embodiment includes a coupling window for electromagnetically coupling the dielectric resonator 21 and the dielectric resonator 24 in addition to a coupling window between adjacent resonators. A coupling window between dielectric resonators not forming a step is provided, and coupling indicated by an arrow B in FIG. 4 occurs. That is, the dielectric resonator 21 and the dielectric resonator 24 are electromagnetically coupled to the three adjacent resonators. Here, the three adjacent resonators are the two resonators constituting the front and rear stages with respect to the resonator, and the one located closest to the three resonators formed in the adjacent row. One resonator. In addition, the coupling between the resonators that do not form the front and back stages as shown by the arrow B is called interlaced coupling.

  A filter having a coupling window between resonators constituting interlaced coupling has a transmission characteristic including a transmission zero in the transition region between the pass band and the cutoff band, and thus functions as a dielectric filter having a steep cut characteristic. To do. Further, by forming the position of the coupling window between the resonators that do not form the front and rear stages on the inner wall of the cavity between the dielectric resonators other than the dielectric resonator 21 and the dielectric resonator 24, transmission characteristics can be improved. The transmission zero can be provided only on the high frequency side or the low frequency side with respect to the pass frequency band.

(Example)
The transmission characteristics of the dielectric filter according to the present invention are shown in FIGS.

  FIG. 5 is a graph showing the transmission characteristics of the dielectric filter of the present invention. In this example, the dielectric filter 81 shown in the second embodiment was used.

  In FIG. 5, a solid line 71 indicates the transmission characteristic of the dielectric filter according to the present invention. For comparison, the transmission characteristic of a conventional dielectric filter constituted only by a dielectric resonator is shown by a broken line 72.

  As shown by the broken line 72, the conventional dielectric filter has a frequency band in which the transmission characteristics increase not only in the pass band but also in the pass band near 2.6 GHz, such as near 3.3 GHz and 4 GHz. When unnecessary waves in these frequency bands are input to the dielectric filter, they are output without being sufficiently attenuated, resulting in spurious generation.

  On the other hand, as indicated by the solid line 71, the transmission characteristic of the dielectric filter 81 according to the present invention is sufficiently low except in a frequency band other than 2.6 GHz. Therefore, even when an unnecessary wave outside the desired frequency band is input to the dielectric filter 81, the unnecessary wave is surely attenuated by the dielectric filter 81.

  FIG. 6 is a graph showing transmission characteristics and reflection characteristics of the dielectric filter in the vicinity of the pass frequency band.

  In FIG. 6, a solid line 74 shows the transmission characteristics of the dielectric filter according to the present invention. A broken line 75 indicates the reflection characteristic of the dielectric filter according to the present invention.

  As indicated by the solid line 74, the transmission characteristic of the dielectric filter 81 is a good value close to 0 dB in the vicinity of the passband 76. In addition, the reflection characteristic in the pass band 76 has a sufficiently small value of −20 dB or less as indicated by the broken line 75.

  FIG. 7 is a graph showing transmission characteristics of the dielectric filter in the pass frequency band.

  In FIG. 7, a solid line 77 indicates the transmission characteristic of the dielectric filter according to the present invention. For comparison, the transmission characteristic of a conventional filter constituted only by a semi-coaxial metal resonator is shown by a broken line 78.

  As indicated by a solid line 77, the transmission characteristic of the dielectric filter 81 according to the present invention has a good transmission characteristic of −0.5 dB or more in almost all bands from 2.58 GHz to 2.6 GHz. Further, as indicated by a broken line 78, a filter composed of only a conventional semi-coaxial metal resonator has a transmission characteristic of about -1 dB in almost all bands from 2.58 GHz to 2.6 GHz. Therefore, the dielectric filter 81 according to the present invention has the characteristic of suppressing unnecessary waves in the same manner as the conventional filter constituted only by the semi-coaxial metal resonator, and the insertion loss as in the conventional dielectric filter. Is small and has good transmission characteristics.

  As described above, the dielectric filter 81 of the present invention not only has the effect of the dielectric filter 1 according to the first embodiment described above, but also two semi-coaxial metal resonances that form adjacent stages. In addition to the coupling of the resonators 25 and 26 and the dielectric resonators 21 to 24, the interlaced coupling in which the two resonators other than the preceding and following stages are coupled is generated. Thus, radio waves outside the desired frequency band can be reliably attenuated. In addition, since the insertion loss before and after the pass band increases rapidly, the number of resonators installed in the housing can be reduced.

  In the above description, the case where the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 are mainly installed in the housing 2 has been described. However, the present invention is not limited to this. In addition, a circuit having a function other than a filter, such as an amplifier circuit or a modulation / demodulation circuit, may be formed.

  In the above description, the case where the coupling window is formed on the upper part of the cavity inner wall between the adjacent resonators is not limited to this, but the lower part of the cavity inner wall between the resonators where the coupling window is adjacent. It may be formed. Alternatively, the coupling window may be formed so as to penetrate the cavity inner wall between adjacent resonators in the vertical direction. In this case, the degree of coupling between adjacent resonators is determined according to the width of the formed window.

  Further, the coupling degree may be adjusted by adjusting the distances between the semi-coaxial metal resonators 25 and 26 and the dielectric resonators 21 to 24 adjacent to each other.

  In the above description, the case where both the dielectric resonator and the semi-coaxial metal resonator have a cylindrical shape has been described. However, the semi-coaxial metal resonator may have a shape other than a cylindrical shape.

  FIG. 8 is a cross-sectional view schematically showing another example of the shape of the semi-coaxial metal resonator according to the present invention, and is a view of the resonator in the first row from the input side connector 3 side. As shown in FIG. 8, the semi-coaxial metal resonator 83 has a step shape. The dielectric resonator 84 has a cylindrical shape as in the above embodiment.

  In the above description, the case where the coupling adjusting screws 31 to 35 are installed between the resonators has been described. However, the coupling adjustment screw is not necessarily installed between all the resonators, and may be installed on the lid portion 2b of the housing 2 as necessary.

  In the above description, the case where the frequency adjusting screws 41 to 46 are installed on the dielectric resonators 21 to 24 and the semi-coaxial metal resonators 25 and 26 has been described. However, the frequency adjusting screw does not necessarily have to be installed on all of these resonators. Further, when the frequency adjustment of the dielectric filter is not necessary, the frequency adjusting screw may not be installed in the housing 2.

  As described above, the dielectric filter according to the present invention is small and has the effect of suppressing unnecessary waves without degrading the Q value of the dielectric resonator, and can be applied to the communication field and the like. It is useful as a dielectric filter having an effect.

It is a perspective view which shows typically the structure of the dielectric material filter in the 1st Embodiment of this invention. It is sectional drawing in the filter part of the 1st line of FIG. It is a figure which shows the operation mode of a resonator, (a) is a figure which shows the operation mode of a semi-coaxial metal resonator, (b) is a figure which shows the operation mode of a dielectric resonator. It is a circuit diagram which shows the structure of the dielectric material filter in the 2nd Embodiment of this invention. It is a graph which shows the transmission characteristic of the dielectric material filter of this invention. It is a graph which shows the transmission characteristic and reflection characteristic of a dielectric filter in the vicinity of a pass frequency band. It is a graph which shows the transmission characteristic of the dielectric material filter in a pass frequency band. It is sectional drawing which shows typically the other example of a shape of the semi-coaxial metal resonator of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric filter 2 Housing | casing 2a Housing | casing main body 2b Cover part 3 Input side connector 3a Inner conductor 4 Output side connector 21 thru | or 24 Dielectric resonator 25, 26 Semi-coaxial metal resonator 31 thru | or 35 Coupling adjustment screw (coupling adjustment element) )
41 to 46 Frequency adjusting screw (frequency adjusting element)
51-56 cavity inner wall 61-65 coupling window 81 dielectric filter

Claims (6)

In a dielectric filter comprising a conductive casing forming a closed space, and a plurality of dielectric resonators installed in the casing and spaced apart from each other,
A plurality of semi-coaxial metal resonators spaced apart so as to be electromagnetically coupled to any one of the plurality of dielectric resonators;
A coupling adjusting element that adjusts the degree of coupling between the plurality of adjacent dielectric resonators and the plurality of semi-coaxial metal resonators;
A dielectric filter comprising: at least one dielectric resonator and a frequency adjusting element that is disposed above the semi-coaxial metal resonator and adjusts a resonance frequency. The dielectric resonator has a shape that is the same operation mode as the semi-coaxial metal resonator,
The housing includes an input / output element for exciting at least one of the semi-coaxial metal resonator and the dielectric resonator in an operation mode of the semi-coaxial metal resonator. Item 2. The dielectric filter according to Item 1.   The plurality of semi-coaxial metal resonators and the plurality of dielectric resonators are disposed on the same surface of the inner wall of the casing forming the closed space. The dielectric filter as described.   The plurality of semi-coaxial metal resonators and the plurality of dielectric resonators adjacent to each other are partitioned by a conductive wall in which a coupling window for adjusting the degree of coupling is formed. The dielectric filter according to claim 1.   5. The dielectric filter according to claim 1, wherein the degree of coupling is adjusted by adjusting a distance between the plurality of semi-coaxial metal resonators adjacent to each other and the plurality of dielectric resonators. 6. .   At least two or more of the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators are mutually connected to three adjacent resonators of the plurality of semi-coaxial metal resonators and the plurality of dielectric resonators. 6. The dielectric filter according to claim 1, wherein the dielectric filter is partitioned by a conductive wall having a coupling window so as to be electromagnetically coupled.